TG coupled with spectroscopic gas analysis is demonstrated to be a powerful tool for the investigation of gas evolution from the thermal decomposition of materials. It delivers a detailed insight into the thermal behavior of the materials characterized by the in situ FTIR spectroscopic evolved gas analysis. The online coupling ensures not only the determination of pyrolysis gases but also the release relative intensity during the decomposition. Therefore, using different gas analyzing methods like MS and FTIR increases the unambiguous interpretation of the results.